Individuals buy and use a hair shampoo for its cleansing properties. Hair shampoos generally are formulated with highly effective synthetic surfactants, like anionic surfactants, to thoroughly clean the hair. Shampoos usually neither aid in detangling wet hair; nor impart any residual conditioning benefits to dry hair, such as manageability or styleability of hair sets; nor impart any other desired physical or esthetic properties to the hair.
Consequently, shampooed hair normally is left in a cosmetically-unsatisfactory state after washing with an anionic surfactant-based hair shampoo. Anionic surfactants not only remove the dirt and soil from the hair, but also remove essentially all of the sebum naturally present on the surface of the hair fibers. Therefore, the desirable properties of anionic surfactants that effectively clean the hair also serve to leave the hair in a cosmetically-unsatisfactory condition. In general, hair shampoo compositions containing anionic surfactants, or nonionic surfactants or amphoteric surfactants, leave the hair with an undesirable harsh, dull and dry touch, or feel, usually called "creak", after the hair is shampooed and then rinsed with water.
Furthermore, thoroughly cleansed hair also is extremely difficult to comb, in either the wet or dry state, because the individual hair fibers tend to snarl, kink, and interlock with each other. In addition, incompletely dried hair, such as hair dried with a towel, has poor brushing properties. Furthermore, the combing or brushing property of the hair remains poor, and the hair has undesirable electrostatic properties in a low humidity atmosphere that causes the hair to "fly away", thereby further reducing the brushing properties of the hair. The unsatisfactory combing or brushing property of hair immediately after shampooing, or during trimming treatments after shampooing, also causes hair damage, such as split ends or hair breakage. In addition, the natural luster and resiliency of the hair is reduced. Consequently, the overall unsatisfactory condition of the shampooed hair usually necessitates a subsequent post-shampoo treatment of the hair with a special conditioning composition to improve these undesirable physical characteristics. These conditioning compositions normally are applied separately from the hair shampoo, and usually are rinses, or cream-like emulsions or lotions.
Therefore, consumer needs traditionally have been met by the application of a shampoo to cleanse the hair, followed by the application of a conditioner composition to improve wet combing. The commonly accepted method has been to shampoo the hair, followed by rinsing the hair, and then separately applying a conditioner composition. The conditioner composition either is allowed to remain on the hair after application (leave-on composition), or is rinsed from the hair after application (rinse-off application). The leave-on hair conditioner composition often are gel materials of relatively high viscosity. As previously discussed, freshly shampooed hair is inclined to knot and tangle, and therefore is difficult to comb and difficult to manage. The combing problem has been solved by treating shampooed hair with a conditioner composition that coats the hair shaft and causes the individual hair shafts in a tress to resist tangling and matting because of the conditioner residue retained on the shaft.
In addition to conditioning the hair, consumers often desire to treat the hair with other types of hair treating compositions, such as, for example, a protection gel including a sunscreen or a hair gel including dyes to temporarily or semipermanently color the hair. The above-described hair conditioners, protection gels, hair fixatives and colorant hair gels often are applied as a leave-on composition, wherein the consumer applies the composition to the hair with the fingertips and does not subsequently rinse the composition from the hair.
The hair treatment compositions described above often include a water insoluble hair-treating compound to treat the hair, such as a silicone conditioning compound or a semipermanent dye. However, such water insoluble hair-treating compounds are difficult to incorporate into an aqueous composition. One well-known method of incorporating the water-insoluble compound into the composition is to provide an opaque, emulsified composition. However, consumers often desire a transparent composition, primarily for esthetic reasons.
It is difficult however to incorporate a water insoluble compound into an aqueous composition and to retain both visual clarity and product performance, such as sufficient hair conditioning or protection of the hair from the sun. To achieve these goals, formulators have used encapsulated water insoluble compounds, and included the encapsulated compound in the hair treatment composition.
Encapsulation is the process wherein a water insoluble compound is encased in a shell material to provide a capsule of sufficiently small size such that the transparency of an aqueous composition is maintained. The encapsulated water insoluble compound does not contact the aqueous carrier, and composition transparency and performance are not reduced.
During or after application to the hair, the capsule is broken due to pressure, friction, or a similar physical process. The broken, or fractured, capsule releases the water insoluble hair-treating compound and the fractured shell particles cling to the hair. For a leave-on composition, the fractured shell particles are not rinsed from the hair. Therefore, a serious disadvantage demonstrated by leave-on compositions is the residual shell particles on the hair which are visible and decrease the shine of the hair, thereby adversely affecting the hair. Rinse-off compositions do not exhibit this disadvantage because the visible residual shell fragments are rinsed from the hair. Therefore, it would be advantageous to provide a leave-on encapsulated hair-treating composition that leaves the hair in an as good an esthetic condition as a rinse-off encapsulated hair-treating composition. Until the composition and method of the present invention, no such leave-on hair-treating composition has been available.
Prior patents have disclosed hair care compositions including encapsulated water insoluble compounds. For example, Mausner U.S. Pat. No. 4,126,174 discloses a shampoo-conditioner composition that simultaneously shampoos and conditions the hair. The composition includes a mineral oil conditioning agent encapsulated in gelatin. By definition, the shampoo-conditioners disclosed by Mausner must be rinsed from the hair. Therefore, the problem of residual shell fragments on the hair was neither considered nor addressed by Mausner because the disclosed composition, and the gelatin shell fragments, are rinsed from the hair. Mausner did not consider leave-on conditioning compositions, and did not teach that the disclosed rinse-off compositions could be used as a leave-on composition.
Only leave-on hair treatment compositions present the problem of large residual shell fragment particles remaining on the hair. Until the method of the present invention, no known investigator has studied the effects of residual shell fragments on the hair. Surprisingly and unexpectedly, it has been found that large residual shell fragments adversely affect hair properties.
Present day leave-on hair care compositions leave sufficiently large fractured shell particles on the hair such that the particles reflect light and therefore give the hair an unsightly and dull appearance. In addition, the large shell fragment particles catch on combs and reduce hair combability. Such adverse effects at least partially, and often significantly, offset the desired properties imparted to the hair by the water insoluble hair-treating compound, and thereby reduce composition effectiveness. In accordance with an important feature of the present invention, this previously unrecognized disadvantage in a leave-on composition that includes encapsulated compounds has been addressed and overcome.
Noda et al. U.S. Pat. No. 5,089,269 discloses cosmetic compositions comprising microcapsules including a hydrophobic component in a gelatin shell swollen with water. Noda et al. disclose several methods of manufacturing microcapsules having variable shell properties and core contents. Noda et al. teaches that a suitable mixture within the capsule reduces the undesirable feel of capsule fragments after breakage. Noda et al. do not teach rupture of the capsules into sufficiently small fragments that cannot be seen.
There is a significant difference between feeling a capsule shell fragment and seeing a capsule shell fragment. The encapsulated product can be formulated to overcome the gritty feel of capsule shell fragments, without addressing the presence of relatively large shell fragments that are visible. Therefore, encapsulated hair-treatment compositions can be formulated to rupture and to provide shell fragments that are visible on the hair but cannot be felt. The publication "Modern Cosmetic Liquids", R. Huttinger, Goldschmidt Chemical Co. 3/81. Nr. 55' English Ed., pp. 31-37, discloses that it is common to use a good spreading compound to overcome the gritty feel of shell fragments. Such a technique is used by Noda et al, wherein the encapsulated compound reduces the "feel" of gelatin shell material.
Other exemplary patents relating to hair treatment compositions including an encapsulated water insoluble compound are Melnik et al. U.S. Pat. No. 5,082,661 and Tanner European Patent Publication No. 0261754.
As will be demonstrated more fully hereinafter, a clear leave-on hair treatment composition of the present invention, comprising an aqueous suspension of transparent capsules including a water insoluble hair-treating compound encased in a shell material such as gelatin or acacia gum, effectively delivers the water insoluble hair-treating compound to the hair. Surprisingly and unexpectedly, the capsules, after rupture to release the water insoluble hair-treating compounds, disintegrate into sufficiently small fragments such that the residual shell fragment particles are not visible on the hair and do not adversely affect the physical or esthetic properties of the treated hair.